Sonoma County foreclosures have dropped to their lowest level in six years, a decrease attributed partly to a new state law regulating the practice.

One hundred fifty-four homeowners lost houses and condominiums to foreclosure in the first quarter of the year, according to San Diego information service DataQuick.

That was a decrease of 42.8 percent from the previous quarter and the lowest for any such period since 94 homes were lost in foreclosure auctions in the first quarter of 2007.

Foreclosures already had steeply declined in the county last year. But analysts suggested that banks started the year taking back homes at an ever slower pace as they adjusted to a new state law that took effect Jan. 1, the Homeowners Bill of Rights.

“Default notices fell off a cliff in January, then edged up,” said DataQuick President John Walsh.

The number of foreclosures still may pick up somewhat later this year, he said, “if lenders need to play a lot of catch-up.”

Foreclosures peaked in the county in 2008, when 2,800 homes were lost at auction.

In the past five years nearly 10,000 property owners have lost houses and condos to foreclosure. By last year the number of foreclosures had declined to slightly more than 1,200.

The number of default notices, the first step in the foreclosure process, numbered 194 in the county for the quarter. That amounted to a 57.1 percent decline from the previous quarter and a 72.2 percent decrease from a year earlier.

For the state, most of the loans going into default are still from 2005 to 2007 — likely the peak period of weak underwriting standards for mortgages, DataQuick reported.

In the first quarter, California foreclosures declined 55.1 percent from a year earlier to 13,591, and default notices decreased 67 percent to 18,567.

Investors statewide purchased an estimated 47.6 percent of the properties taken to auction in the first quarter, according to DataQuick. A year earlier, the estimate was 33.7 percent.

— Robert Digitale